INTERNATIONAL TRANSACTIONS

I would like to ask fellow audiogoners about your experience on international transactions.
1. Does US Custom charge certain duties or import taxes on USED electronics bought from other countries like Japan,Indonesia as they arrived here in the USA. If so Any idea how much???
Full price of the unit has to be disclosed for insurance purposes.
2. Best carrier/shipping freight
3. Please direct or lead me to the right site for more information about this matter.
Thanks